Worried that you're using too much petrol? Concerned that if you crashed your car in a remote location nobody would find out until too late? A new breed of software apps – linked to devices that plug directly into a car's computer – could put your mind at rest.

The RAC has announced it will begin selling a small box called Advance that can monitor data – speed, fuel efficiency, airbags, lights, brakes and more – and provide feedback. It plugs into the on-board diagnostics connection included in all cars built in Europe since 2001.

The RAC has installed the matchbox-sized device in 1,700 patrol vehicles and plans to sell them to customers later this year. The organisation's commercial director, Kerry Michael, said: "We would be able to remotely monitor the car so that if you've left your lights on, we'd be able to send you an alert to warn you."

For those who don't want that, but do want to know what's happening inside their engine, an alternative was recently announced in the US. Automatic, a California-based company, unveiled Automatic Link, a little box costing $69.95 (£46) that plugs into the same diagnostics slot and transmits the same readings directly to your smartphone. You'll be able to see your fuel efficiency, mileage, get warnings about any problems with the car and – once you're parked – have a marker on your smartphone's map recording where you left the vehicle.

"It could do for driving what the iPod did for music," said CNBC technology writer Jon Fortt. He reported that the app even gave a score out of 100 for the fuel efficiency of his driving.

Both systems offer an "emergency call" facility: if the box detects a huge deceleration and airbag deployment, it will know you've had a crash and call an emergency service with your location. For the RAC, a sim card in the box will send readouts from the engine's computer to breakdown offices and patrol vehicles, which should save time in diagnosing problems.

That two companies based in different continents have announced the products at the same time is another sign of the rise of the "quantified self" movement, whereby people measure as much as they can about themselves and everything around them. Whether they want to know the number of steps they take, hours they sleep or calories they eat, apps are springing up to cater to them.

Automatic, which was founded in 2012, has already got venture capital backing from Andreessen Horowitz, which has previously invested in Twitter, Skype and several other venture capital companies. When its website went live a few days ago, the reaction was hugely positive. "We've been amazed by the reaction, both here in the US and internationally," said an Automatic spokesperson. "It's gratifying to know that we're working on something people are so excited about."

Although a number of companies, such as British-based Masternaut, already offer systems to measure the performance of fleet vehicles, until now they have been comparatively expensive and required special fitting. The RAC's box, made to its own specifications and built in the US, and the Automatic Link are both simple enough that drivers should be able to install them without help.

For drivers it could mean huge savings on fuel: the RAC believes the average motorist could save up to £620 a year by driving more equably.

The data could also affect insurance claims. Police and insurance companies could, for example, seek access to data from the RAC or the Automatic app through a court order, which could reveal how fast the vehicle was going before a crash. "It's the same as the tachograph used in lorry cabs," said Michael. "That's been in widespread use for years. This technology is going to go the same way."

Although Automatic Link isn't yet on sale outside the US, it would work on cars in Europe as long as they had onboard diagnostics.

Automatic's founders, Thejo Kote and Jerry Jariyasunant, met as graduates at the University of California, Berkeley, where they were researching computer science, human-computer interaction and transportation systems. Just as Larry Page and Sergey Brin noticed in 1996 that online search wasn't much good and built Google, Kote and Jariyasunant noticed that drivers did not take much notice of how much time and money they spent driving or how they could cut both down.

"We knew we had to build our own hardware to give them feedback while they drive, and from there many other possibilities for helping people drive smarter opened up," said Kote.

The RAC has not announced a price or launch date for Advance, though Michael said it would be soon.